A plasma etching apparatus is required to satisfy the following point; specifically, it is important to configure the foregoing apparatus so that particles generated during etching do not adhere onto a substrate. In particular, in a plasma etching process for forming a photomask pattern, it is extremely important to prevent adhesion of particles in order to form a pattern having no defect. Moreover, the following proposal has been made; specifically, a plasma etching apparatus is provided with an electrode cover for protecting an electrode from plasma (e.g., see Jpn. Pat. Appln. KOKAI Publication No. 2006-332336).
However, according to a conventional case, the optimum structure for preventing adhesion of particles has not been proposed in a plasma etching apparatus provided with an electrode cover.